Irregular tooth spacing reduces tracking of roller cone bits

Conference · Sun Sep 01 04:00:00 EDT 1996

OSTI ID:287844

Kenner, J V ^[1]; Boylan, T P ^[2]

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1. Hughes Christensen Co., Houston, TX (United States)
2. Transatlantic Technical Services, Houston, TX (United States)

Tracking, which occurs when teeth fall in to the craters formed during previous bit rotations, severely impacts the performance of roller cone rock bits. The tracking tendencies of tungsten carbide insert (TCI) bits are generally considered once the bit is built and tested, rather than during the design process. Once tracking is initiated, crater depth quickly reaches the full projection of the teeth, bringing the cone steel in contact with the rock. This increases the contact area while reducing contact stresses beneath the inserts. Tracking increases the likelihood that neighboring rows of cutters will line up on the hole bottom forcing the bit to rotate about a point other than its geometric center--a phenomenon referred to as off-center rotation or forward whirl. Off-center rotation produces rings of uncut bottom and a further reduction in contact stresses. This paper discusses laboratory and field data used in the development and validation of a proprietary algorithm that determines the optimal tooth spacing to eliminate tracking. This study confirms that an algorithm can be applied effectively in the roller cone bit design process to improve coverage of the rock surface during drilling. In addition, these laboratory tests improve the understanding of a single gear-like wheel, a prerequisite to understanding total bit behavior.

• OSTI ID: 287844
• Report Number(s): CONF-960154--; ISBN 0-9648731-8-4
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
42 ENGINEERING
COMPUTER-AIDED DESIGN
CUTTING TOOLS
DRILL BITS
FIELD TESTS
OIL WELLS
OPERATION
PERFORMANCE
POSITIONING
SIMULATORS
TUNGSTEN CARBIDES
WELL DRILLING